How to Measure Connector Pitch: JST & Molex Identification Guide

Connector pitch — the center-to-center distance between adjacent pins — is the single most important measurement for identifying an unknown connector. Get it wrong and you'll order the wrong parts. This guide walks you through exactly how to measure connector pitch and identify common JST and Molex series.

What Is Connector Pitch?

Pitch is the distance from the center of one pin (or contact) to the center of the adjacent pin, measured in millimeters. It is the primary specification used to identify and match connector series.

Key points:

• Pitch is always measured center-to-center, not edge-to-edge
• Two connectors must have the same pitch to mate
• Same pitch does NOT mean interchangeable — housing shape and locking mechanism also matter
• Common pitches range from 1.0mm (ultra-compact) to 4.2mm (high-current power)

Tools You Need

Option 1: Digital Caliper (Recommended)

A digital caliper is the most accurate and reliable tool for measuring connector pitch. Any caliper with 0.01mm resolution is sufficient.

• Accuracy: ±0.02mm — sufficient to distinguish 1.0mm from 1.25mm pitch
• Best for: All connector sizes, especially fine-pitch (SH, GH, ZH)
• Tip: Use the inside jaws to measure between pin centers on a PCB header

Option 2: Ruler + Calculation

For larger connectors (XH 2.5mm, VH 3.96mm), a standard ruler can work:

1. Measure the total width across N pins (outer edge to outer edge)
2. Subtract one pin diameter
3. Divide by (N−1)

This method is less accurate for fine-pitch connectors and is not recommended for SH/GH/ZH series.

Option 3: Visual Comparison

If you have a known reference connector, you can visually compare pitch. This works for experienced users but is prone to error for similar pitches (e.g. 2.0mm vs 2.54mm).

Step-by-Step: How to Measure Pitch with a Digital Caliper

1. Identify the connector type — determine if it is a housing (plastic shell) or a PCB header (pins on board)
2. Count the pins — note the total pin count for later reference
3. Measure across multiple pins for accuracy — place caliper tips at the center of pin 1 and the center of pin N
4. Calculate pitch — divide the measured distance by (N−1). Example: 5 pins, total span = 10.0mm → pitch = 10.0 ÷ 4 = 2.5mm
5. Cross-reference the pitch table below — match pitch to connector series
6. Verify housing shape and locking mechanism — confirm the series by comparing physical housing profile

Pro tip: Always measure across at least 3 pins when possible. Measuring only 2 adjacent pins amplifies any caliper placement error.

JST Connector Pitch Reference Table

Pitch	JST Series	Current	Mount	Common Application
1.0mm	SH	1A	SMD	Drones, wearables, laptops
1.25mm	GH	1A	SMD	Flight controllers, FPV
1.25mm	Molex PicoBlade	1A	SMD/TH	Drones, IoT (NOT compatible with GH)
1.5mm	ZH	1A	Through-hole	3D printers, IoT modules
2.0mm	PH	2A	Through-hole	LiPo batteries, Arduino
2.0mm	Molex Micro-Latch	2A	Through-hole	Consumer electronics (NOT compatible with PH)
2.5mm	XH	3A	Through-hole	3D printers, RC vehicles
2.5mm	EH	3A	Through-hole	Slim PCB (NOT compatible with XH)
2.5mm	SM	3A	Wire-to-wire	LED strips (NOT compatible with XH/EH)
2.54mm	Molex KK 254	3A	Through-hole	PC fans, Arduino shields
3.0mm	Molex Micro-Fit	5A	Through-hole	Server power, industrial
3.96mm	VH	10A	Through-hole	Power supply, motors
4.2mm	Molex Mini-Fit Jr.	9A	Through-hole	ATX power supply, PC motherboard

Common Mistakes When Measuring Pitch

Mistake 1: Measuring Edge-to-Edge Instead of Center-to-Center

The most common error. Always measure from the center of one pin to the center of the next. Measuring edge-to-edge gives a result that depends on pin diameter and will not match the nominal pitch.

Mistake 2: Measuring Only 2 Adjacent Pins

With a 2-pin connector, you have no choice. But for 3+ pin connectors, always span as many pins as possible and divide. This averages out any placement error.

Mistake 3: Assuming Same Pitch = Same Connector

This is the most dangerous mistake. Multiple connector series share the same pitch:

• 2.5mm pitch: JST XH, JST EH, JST SM — all different, none interchangeable
• 1.25mm pitch: JST GH, Molex PicoBlade — NOT compatible
• 2.0mm pitch: JST PH, Molex Micro-Latch — NOT compatible
• 2.54mm pitch: Molex KK 254, Molex SL, DuPont — different housings

After measuring pitch, always verify the housing shape, locking mechanism, and contact orientation before ordering.

Mistake 4: Confusing 2.5mm and 2.54mm

JST XH uses 2.5mm pitch. Molex KK 254 and DuPont use 2.54mm pitch. The difference is only 0.04mm — impossible to distinguish by eye and difficult even with a caliper. Check the housing profile and manufacturer markings to confirm.

Mistake 5: Measuring a Crimped Cable Instead of the Housing

Crimped wire spacing can vary slightly due to cable flex. Always measure the housing or PCB header, not the wires.

Quick Identification Checklist

After measuring pitch, use this checklist to confirm the connector series:

1. ✅ Pitch measured (center-to-center, across 3+ pins)
2. ✅ Pin count noted
3. ✅ Mount type identified (SMD / through-hole / wire-to-wire)
4. ✅ Housing profile compared (height, width, latch position)
5. ✅ Locking mechanism checked (friction / side latch / positive latch)
6. ✅ Manufacturer marking checked (if visible on housing)

For a complete walkthrough of the identification process, see our JST connector identification guide.

Pitch by Application: Quick Reference

Application	Typical Pitch	Connector Series
FPV drone / flight controller	1.0–1.25mm	JST SH / GH
LiPo battery (small)	2.0mm	JST PH
3D printer / RC battery	2.5mm	JST XH
LED strip	2.5mm	JST SM
Arduino / breadboard	2.54mm	Molex KK 254 / DuPont
PC fan	2.54mm	Molex KK 254
High-current power	3.96–4.2mm	JST VH / Molex Mini-Fit Jr.

Related Guides

• 📌 How to Identify JST Connectors: Pitch, Series & Pin Count Guide
• 📌 JST Connector Types: Complete Guide to SH, GH, PH, XH, VH & More
• 📌 Molex Connector Types: Complete Guide to Series & Applications
• 📌 JST XH Connector: Complete Guide & FAQ
• 📌 Brass vs Phosphor Bronze Connector Contacts: Which Material Should You Choose?

Frequently Asked Questions

What is the most common JST connector pitch?

The most common pitches are 2.0mm (JST PH) and 2.5mm (JST XH). PH dominates battery and sensor applications; XH is the standard for 3D printers and RC vehicles.

Can I use a ruler instead of a caliper to measure pitch?

For larger connectors (2.5mm+), a ruler can give a rough measurement. For fine-pitch connectors (1.0mm, 1.25mm, 1.5mm), a digital caliper is essential — the differences are too small to measure accurately with a ruler.

How do I tell JST XH (2.5mm) from Molex KK 254 (2.54mm)?

The 0.04mm pitch difference is nearly impossible to measure reliably. The easiest way is to compare the housing profile: JST XH has a distinctive rectangular housing with a top latch, while Molex KK 254 has a different housing shape. Check manufacturer markings on the housing if visible.

Where can I buy JST connectors once I've identified my pitch?

Browse our connector collections by pitch: 1.0mm SH, 1.25mm GH, 1.5mm ZH, 2.0mm PH, 2.5mm XH, 3.96mm VH. Ships worldwide with no minimum order quantity.